The present invention relates to a microcomputer and, more particularly, to a microcomputer comprising a nonvolatile flash memory to and from which data may be written and erased electrically.
Illustratively, EPROM's are writable nonvolatile memories whose data is erased by use of ultraviolet rays. This means that these memories need to be detached from the systems incorporating them for the erasure and writing of data therefrom and thereto.
By contrast, flash memory EEPROM's have data written and erased thereto and therefrom electrically. It follows that these memories may remain installed in their respective systems while the memory data is being updated.
One means for updating data in the EEPROM's is a serial communication interface. In the typical serial communication setup, the baud rate on the host computer side is fixed while the baud rate of the microcomputer using the memory is determined by the operating frequency of the microcomputer. A suitable value representing the baud rate so determined is set in a register of the serial communication interface.